During a 3-month period, determinants of psychotropic drug utilization (sex, age, length of stay, reason for admission, disease severity) and data on psychotropic consumption (type of medication-antidepressants, benzodiazepines and antipsychotics-dosage and length of treatment) were retrospectively collected in a general intensive care unit of a Dutch university hospital.

Daily exposure to psychotropics was standardized in number of Defined Daily Doses (DDD).

Benzodiazepines were used by 35.8% of all patients (137) during their stay in the ICU whereas 17.5% of all patients used a neuroleptic agent.

Antidepressants were hardly prescribed.

High doses of benzodiazepines (9.9 DDDs) and low doses of antipsychotics (0.5 DDDs) were prescribed, which probably reflect the unusual nature of this critically ill group of patients compared with the reference group for DDD's. Clear patterns of determinants of psychotropic drug use in ICU patients were found and both benzodiazepines, antipsychotics and combined use of these agents could be associated with the determinants assessed.

The time patterns we found in terms of length ofstay give clues for further investigations in order to rationalize psychotropic drug use in the management of severely ill and complex patients.